Shaun Murphy fought back against the defending champion, Zhao ­Xintong, to lead 5-3 after the opening session of their World Snooker Championship quarter-final at the Crucible.

Zhao had started with a break of 122 and soon moved 3-0 ahead. Former champion Murphy – who won his second-round match against Xiao Guodong with a session to spare – took the fourth frame after a composed break of 69 before the mid-session interval. Murphy then capitalised on Zhao’s break finishing at 56 to clinch the next after clearing the final five colours to further reduce the deficit.

A scrappy sixth frame littered with errors from both men lasted more than 40 minutes, during which Murphy potted the final red on his fifth try from a snooker behind the yellow, bouncing the cue ball off the side cushion and down to clip the red into the far corner. Zhao then went on to miss a frame-ball pink that allowed Murphy back in to take it 74-70. Murphy then edged ahead in the match for the first time after Zhao failed with a powerful attempt on the brown.

The unforced errors continued in a nervy final frame of the session, with Murphy missing a green into the top pocket when ­needing only up to the blue. Zhao, though, saw his shot on the pink with the rest rattle the jaws, handing Murphy the chance to knock it in and win 59-44.

In the afternoon’s battle of the former ­champions, Neil Robertson took a 5-3 lead over John Higgins. After the pair were locked at 2-2 heading into the mid-session interval, Robertson edged ahead with a 70in the fifth frame.

Maintenance were called in to fix Robertson’s chair seat before the next frame, which saw the ­Australian left in a difficult snooker behind the yellow. It took him six attempts to escape, leaving Higgins – who had knocked out Ronnie O’Sullivan in a dramatic last-frame decider – 37 points clear before the four-time former world champion finished off the reds.

Robertson then edged a nervy seventh frame 70-62 on the pink before capitalising a frame later when ­Higgins missed a simple pink having potted a brilliant red. The match will resume on Wednesday morning.

In the other match, Hossein Vafaei fought back to draw level at 4-4 with Wu Yize.

Iranian qualifier Vafaei had beaten the world No 1, Judd Trump, in another thrilling contest which went the distance on Monday night. Wu – who dispatched another former champion Mark Selby 13-11 in the last round – opened up a 4-2 lead after a well-crafted 90 and then back-to-back half-centuries.

Vafaei, though, responded with a break of 71 and then came from behind to edge a tense eighth frame 56-44. The match will resume on Wednesday afternoon.

On the other table, Barry Hawkins took a 5-3 lead over Mark Allen. Hawkins – who ended the hopes of former champion Mark Williams in the last round – made a break of 114 in the second frame and three more half-centuries took him clear as Allen’s mistakes proved costly.